Israelis woke up to yellow skies heavy with sand blowing in from the east Wednesday as a dust storm lingered for a second day, with temperatures rising across the country and adding to the already difficult weather conditions.

Some domestic flights were canceled due to low visibility for a second day. The Israeli airlines IsraAir and Arkia each announced that buses would be available for travelers to Eilat on Wednesday, as scheduled flights were postponed. The airlines said they will reassess as necessary throughout the day.

The Environmental Protection Ministry reissued its warning Wednesday to avoid being outside for extended periods and nix any physical activity outdoors.

Temperatures are also expected to reach 100 degrees Fahrenheit (38 Celsius) and higher in some parts of the country, including Jerusalem.

According to estimates, the storm is set to pass before the weekend and temperatures will drop slightly as the Jewish High Holidays approach early next week.

On Tuesday, hundreds of people in Israel were treated for respiratory problems and other weather-related ailments.

Israel’s emergency medical service Magen David Adom reported that 340 Israelis received medical treatment as a result of the weather, including those suffering from asthma, respiratory problems, shortness of breath and heart issues.

“The MDA will continue to be on alert in light of the heatwave and dust storm,” MDA Director General Eli Bin said.

He urged Israelis to stay indoors, warning that the storm poses a real danger to people’s health, and asked that schools keep children indoors.

The dust has been making its way to Israel from Iraq and Syria over the past week.

Jerusalem on Tuesday recorded its worst air pollution levels ever, at 173 times normal levels, according. In some other parts of the country, air pollution levels were at their worst for 75 years.

Some 800 kilometers above the earth’s surface, NASA satellite images show Israel, Egypt’s Sinai Peninsula, Jordan, Lebanon and parts of Syria covered in the thick brownish-yellow fog. According to the satellite data, the dust cloud rose 600 meters in the air.

In Israel, the concentration of sand particles was highest in the hills, including the Jerusalem area, the southern West Bank and the Golan Heights. In Jerusalem, pollution levels were 173 times higher than the average; in the Negev, 51 times higher; and in the Galilee, 32 times higher.

The dust storm also hit Lebanon’s coastal capital of Beirut on Tuesday, leaving four people dead, and people have been advised to stay indoors.

The Lebanese state news agency said at least 750 people fainted or suffered breathing problems because of the fine dust.